100,000 Mile Transmission Flush and Service Questions

[WildernessJeep]

Dealing with a 2005 Yukon Denali AWD, with 110,000 miles. The FSM says that at 100,000 miles I am supposed to flush the transmission and change the transfer case fluid. I'm cool with the transfer case fluid, that's just a drain and replace. I can't imagine the transfer case has a filter.

I know that about 1/3rd of the fluid is hung up in the valve body on most transmissions, and that a simple drain and refill generally won't get it. Plus, I have to change the filter too. Is this something that I should take to a shop for? I know that they advertize a "hot flush", but really don't know how hot fluid flushing would be any different from the new fluid once it is warmed up.

Opinions??

 

[Sasquatch]

A lot of guys here agree that a flush isn`t a good thing to do. It may change all the fluid but in the process it stirs up debris that could cause problems later.

I changed my trans fluid with this method and it worked great.

http://www.truckmodcentral.com/forums/f63/how-flush-your-transmission-gmt800-gm-truck-4699/

The only hard part is dealing with the shift linkage bracket, It blocks you from dropping the pan. They`re blind torx bolts and in my case i couldn`t get them loose so i just bent the bracket to get the pan down.

 

[kschumake83]

Do not let them do a pressurized flush on your truck.

Its easy, drop the pan and change the filter. After that don't do anything until you remove one of the oil cooler lines. Put about as much new fluid in the dipstick tube as what came out of the pan. Put the transmission line in a pan and start the truck until about 2 quarts come out. If the line starts shaking stop. Fill 2 quarts into the dipstick tube again and repeat until clean fluid comes out.

There are much better write ups than that out there, I just gave you the nutshell version.

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[Wake]

Trans Fluid Change.

I had one flush in my life on a car 15 years ago, it cost me the tranny not too long after that.

What I do now is change out the trans pan with a drain plug pan and change the pan fluid every other oil change. Right at 5qts came out of the deep pan on my 02 Trailblazer (same 4L60E trans). So it was pretty easy to change out the fluid that way.

You only get around 1/3 of it out this way but doing it so frequently dilutes the old stuff in there. Putting on a pan with a drain plug also makes the filter changes at 50K miles much easier as well.

 

[kschumake83]

+1 my Pontiac had a similarly designed fwd trans and I had it flushed by a shop at 34000 miles. By 36000 I only had 1st gear left. That's why I put in my disclaimer in before my previous post.

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[scottg918514]

A lot of guys here agree that a flush isn`t a good thing to do. It may change all the fluid but in the process it stirs up debris that could cause problems later.

I changed my trans fluid with this method and it worked great.

http://www.truckmodcentral.com/forums/f63/how-flush-your-transmission-gmt800-gm-truck-4699/

The only hard part is dealing with the shift linkage bracket, It blocks you from dropping the pan. They`re blind torx bolts and in my case i couldn`t get them loose so i just bent the bracket to get the pan down.

This, if you want to flush a trans, should be doing it from new. Don't flush a trans after 100k. Drop pan, change filter and replace as much fluid as you get out. Then after 10 k, pump and replace as much as you get from dip stick. Then again after another 10k. After that should be good for another 60k or more, just depends on if you tow or not.

 

[Xshooterx]

So what do y'all recommend for a 60,000 mile tranny. Pressure flush, flush like the link posted earlier, or just change filter and replace what comes out of pan?

 

[kschumake83]

The link posted earlier, I would not do a pressure flush on a gm trans unless I wanted to kill it. If you keep up on regular maintenance you will never need to do more than that. I would actually do what Wake suggested after flushing it good with the method in the link. Doing 5 quarts every so often would seem like the best route to go.

 

[WildernessJeep]

Well, I just hauled a Jeep around Colorado for a week, and drove to Mexico, so I'll do the full flush. This transmission has never filled me with a ton of confidence. It is kind of clunky and occassionally misses a shift (although I have never had a problem under load). Some of that may be transfer case and AWD system lash, but I'm gonna try to take care of the transmission the best I can.

I'll report back once the project is done, and let you guys know how it went.

 

[livingez_123]

Stay away from the quick lube places, they will trash your trans with the system they use. AAmco says at 100k the electronics should be replaced it includes the shift solenoids and the TCC solenoid and the MAP sensor. it's a tune up for your trans.

 

[dcwhybrew]

I've always changed transmission fluid in my cars and haven't ever had a problem. I bought my 06 Yukon last August with 96k. I immediately flushed the transmission fluid. No issues ever. It shifts and runs like new. I haven't ever bought in to the hype of not changing or flushing the fluid. If you read posts on the subject, I doubt you'll find any that state, "I had a transmission failure after flushing / changing my fluid". All the posts I've read state, "I heard, or conventional wisdom is, don't...."

 

[kschumake83]

Here is that post. I had a pressurized flush done on my 03 Pontiac grand Prix. It was a gt model with 34000 miles on it, it shattered everything except for 1st gear and I had to replace the trans by 36000. I will say that I believe in changing the fluid, just don't let a shop blow it in with a machine because it can hurt the trans.

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---------- Post added at 06:53 AM ---------- Previous post was at 06:43 AM ----------

@dcwhybrew, Out of the 7 people who posted in this thread, 2 of us had actual transmission failure after a pressurized flush. So I think you might need to brush up on your reading skills a bit.

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[Sasquatch]

I have a friend that used to be a manager at a speedy lube place that did transmission flushes. I used to hang out there for entertainment watching the under qualified so called mechanics cross thread drain plugs, transmission lines and spark plugs.

In my time there there was at least one person in a week complaining about their transmissions dying after a flush. The owner finally decided to stop doing the flush service due to too many claims from pissed off customers. My brother was one of them so yeah, I`ve seen it and will never tell anyone to get a flush.

 

[dcwhybrew]

Here is that post. I had a pressurized flush done on my 03 Pontiac grand Prix. It was a gt model with 34000 miles on it, it shattered everything except for 1st gear and I had to replace the trans by 36000. I will say that I believe in changing the fluid, just don't let a shop blow it in with a machine because it can hurt the trans.

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---------- Post added at 06:53 AM ---------- Previous post was at 06:43 AM ----------

@dcwhybrew, Out of the 7 people who posted in this thread, 2 of us had actual transmission failure after a pressurized flush. So I think you might need to brush up on your reading skills a bit.

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And you're certain your transmission failure wasn't because you didn't maintain it? And back to my point more often than not, the transmissions are fine.